Method of and apparatus for producing sparkless commutation.



1. EL'LINC OLN.

METHOD OF AND APPARATUS FOR PRODUCING SPARKLESS COMMUTATION.

APPLICAHON FILED MAYS. i913- 1,244,518.

Patented Oct. 30, 1917.

Lm nco Zn fizagfamay STATES PATENT OFFICE.

s, aoga.;ma; w CLEVELAND, OHIO, ASSIGNOR To rnnnmoomv ELECTRIC Qcomrnnr, or CLEVELAND, omo, A CORPORATION 01 01110.

. Be 'it known thatl, JOHN C. LINCOLN, a

, citizen off'the. United States, resident of i'flClev'eland,ocount'ygfof Cuy ahoga, and State of Ohio," have invented a new anduseful Iniprovement. in Methods of and Appa- I-tion, 'the lprfinciple,of the invention being hereinexplained and the best mode in which ihave contemplated applying that princit ons.

I 'ple,.so" asto distinguish it from other inveninvention relates tomethods of and apparatus for producing sparkless commutation, its-objectbeing to increase the efficiency offelectric,apparatus in whichcommutation occurs 'by the elimination of the 1 sparking which usuallyattends such action.

The said invention consists of a method andapparatus "hereinafter fullydescribed and particularly'set forth in the claims.

U f .The annexed drawing and the following :description ,set forth indetail certain means embodying the apparatus forming a part of my inyention, thevdisclosed means, however, constituting butlone of variousmechanical forms in which theprinciple of the invention, both asijrelates to the method and mean's, may be applied.

a This application furthermore constitutes v a ,divisi'on of myapplication, Serial No.

1 [In said annexed drawing, the figure is a pairing castings, in themanner fully (lo-- Specification of Letters Patent.

part C of greater cross-section.

. I Mnrnon 01 AND APPARATUS r03 PRODUCING SPARKLESS OOMMUTATION.

Patented Oct. 30, 1917.

ed February 2, 1912, Serial No. 874,892. Divided and this applicationfiled Kay 5,

1913. Serial No. 765,518.

scribed in my above-mentioned pending ap plication. The armature isdrum-wound and of full pitch.

.This field structure is provided with four poles, each of which isdividedinto two parts, a part0 of lesser cross-section, and Thepole-portions C of greater cross-section have two field windings uponthem, a winding D of comparatively high resistance and a winding E ofcomparatively low resistance. The pole-portions C oinsmallercrosssection have wound upon the windings D of resistance similar tothat of the windings D, in series with the latter and connected with'the main brushes F and F These windings D and D are therefore connectedin shunt in the apparatus. a

The windings E of low resistance are in series with each other, asecondary brush G and an exterior arc circuit J Thissecondary brush islocated so as tobe intersected by a plane passing through the axis ofthe armature A and midway between the two pole-portions C and C. Thedirection of the various currents in the field windings are indicated bythe arrows, in the figure.

The direction of rotation of the armature and the direction andarrangement of the windings on the two pole-portions of each completepole-piece are such that the polarity of the armature pole produced atthe secondary or arc-brush G will be of the same signas that of thedivided pole-piece adjacent to which this brush is located. These twopole-portions I furthermore arrange so that they will be separated by aconsiderable distance as shown in the figure, and the respective zonesof the generating and motorwindings of the armature will meet in a planepassing through the axis of the armature andthrough the secondary brush,that is between, and substantially midway be-' generating windings. Thepole-portions C 1 and C are provided with windings such as will, asbefore stated, make them poles of I motor -current.

thesame sign.- That part ofthe armature subtended by the brushes F and Gcarries the generated current and that part subtended. by brushes F andGr carries the That direction of rotation of' the armature is nowselected which,-'as

also before stated, will make the pole formed in the armature at thearc-brush G, of. the

same sign as that of pole-portions C and C. In the machine illustratedthis'sign is N. In order therefore. to produce an N-pole at brush G, thedirection of current in the generatingarmature coils must; b'e'up, as

illustrated, and the direction of thecurrent, in'thatpart of thearmature coils carrying the motor current, must be down, -also asillustrated; The direction of rotationofthe armature in the illustratedexample must therefore be that indicated by the arrow.

It will be recognized by those skilled in the art that a brush-in theposition of brush, G will at no load tend to spark, .due to overcommutation. --The between the two pole-portions issufiiciently great sothat thetendency dies not resultinactual sparking Now as the load comes.on, this arrangement will tend to weaken the two stationary fieldpolesand therefore create a magnetic field through which the armature windingpasses at the instant of short-circuit which is weaker as a result ofwhich they voltage in the coil or coils short-circuited by the arcbrushat the'instant of short-circuit, willhaving anarmature of 161, diameter,by

making the air-gap between the poles and the armature and making thespace between the inner ends. of thepole portions 2% in width. Practicalexperience in building these transformers has'shown that in order .toobtain this sparkless commutation according to my invention, thedistance to be selected as separating the pole-portions should besubstantially the same, in any given transformer, as would be selectedfor themininium distance for separating distwo pole portions.

similar poles in an ordinary dynamo-electric machine of similarmechanical dimension.

Having 'fully described my invention,

what I claim and desire to secure by Let-- 'ters Patent is 1. The methodof securing substantially" sparkless commutation in a 'divided-pole drumwound dynamo-electric machine,

. which consists in withdrawing-currentv from the armature coils at apoint intersected'by a plane passing between twopole-portions' vandthrough the-armatures axis, and caus-' ing "that direction "of armaturerotation which will makev the polarity 'of the same sign "as that ateachof saidtwo pole-portions. 1

2. The method of preventing sparking in a'rotary transformerhaving adivided pole,

a, drum-wound armature, main brushes and an intermediatecurrent-collectin'g brush which consists'in causing such direction ofrotation as will produce at the said intermediate brush, a polarity ofthe armature pole of the same sign as" the polarity of the 3.'The methodof preventing sparking in a rotary transformer having a divided pole adrum-wound armature, main brushes and an intermediate 1currentcollecting brush which consists in causing a direction of rotation andpolarity of poles such that the armature reaction will tend to weakenthe stationary poles.

4. In a rotary transformer, the combination of a drum-wound armature; asuitable commutator; means for creating a magnetic field and includingdivided poles; main brushes and an intermediate brush; the windings ofsaid pole portions, armature and. connections being arranged so that thedirection of rotation will be such that the generated current willproduce a pole in the this 16th day or April,

armature of the same sign as the adjacent field pole pieces.

Signed by me, 1913.

JOHN C. LINCOLN.

Attested by HERMAN Ersnw, D. FINDLING.

